Loud sucking noise – Hotpoint TCFM 90C

Hi

My 3-month-old Hotpoint condensor tumble dryer recently stopped heating with the ’empty tank’ light on continuously.

The engineer said the pump had stopped working and fitted a new one.

Now, after about 15 minutes of drying, there’s an intermittent (5 secs every 30 secs) loud sucking noise coming from back of machine. Louder than the sound of the turning drum. It sounds like someone drinking with a straw, trying to suck up the last drop at the bottom of the cup. But louder.

I called the engineer and he said this is normal operation. I can’t remember hearing it when the machine was new. Any ideas?

Elliot